Column Feeds and Products

Column Feeds and Products - Overview

This window is used to provide various information for column feeds and products that have been drawn on the Piping and Flow Diagram (PRO/II main window) of the simulation. There is no limit on the number of feeds and products a column may have.

Transfer of Overhead or Bottoms Rate Estimate to Specification

Following are the conditions under which Transfer of Overhead or Bottoms Rate Estimate to Specification takes place:

Presence of Reboiler
The Feeds and Products Data Entry Window (DEW) is entered and the Rate for the bottoms and/or the overhead is entered in the Products Grid for first time.
In the absence of condenser, at least one spec/vary pair is present and the specifications are totally incomplete.
In the presence of a condenser, at least two spec/vary pairs are present. Exactly one specification is complete and must be a reflux specification. All the other specifications must be totally incomplete.

When the user clicks the Feeds and Products window, the overhead or bottoms estimates are transferred to specification slots upon user confirmation.

If a condenser is present and reboiler is absent, PRO/II attempts to satisfy the one degree of freedom with a reflux specification rather than a rate specification.

When required data in the Feeds and Products window are entered, clicking OK displays a message box that requests user confirmation.

Select "Yes" to accept the data transfer, "No" to reject it, or press "Cancel" to cancel the action and return to the Feeds and Products DEW.

Automatic Estimate Normalization

Providing estimates for both the overhead and bottom product rates (which may be redundant), initiates automatic normalization of all column products. For the first execution of the column model, the rate estimates are normalized so the summation of all the column products matches the total feed (when the column solves for the first time). For columns in recycle, the same normalization is applied whenever the column was not converged in the immediately previous recycle iteration.

Usage

From the Column Main Window, push the Feeds and Products button.

Feed tray numbers are required for the Column Feed Streams which appear in the list of column feed streams table.

For distillation columns, select the appropriate Feed Flash Convention option. The default selection is to put the feed vapor and liquid on to the feed tray.

The information for product streams is entered via the drop-down list boxes in the list of product streams table. Every column must have an overhead product from tray one and a bottoms product from the highest numbered tray. See Column Product Streams for further details.

Column Pseudoproducts corresponding to tray liquids, tray vapors, pumparound streams, and thermosiphon reboilers may be entered using the Column Pseudoproducts Window, which is displayed when the Pseudoproducts button is pushed.

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